1. Field of Invention
The present application relates to multi-display technology, in particular to a display system and method capable of supporting multi-display.
2. Description of Related Prior Art
With the development of various interface techniques, the notebook as a portable computer is required to support a variety of peripheral interfaces such as USB, serial and parallel port, network interface, VGA/DVI/HDMI interface and Displayport interface in the future. Accordingly, the notebook computer will become complicated and clumsy in order to support all types of these interfaces.
In view of the above issues, a concept has been proposed in the art that is based on the port replicator or docking station. That is, a peripheral device is designed as an attachment to the notebook computer and placed near the computer or under the base of the computer in a wired way, such as USB/PCIe, or in a wireless way, such as UWB. All kinds of interfaces can be integrated into the peripheral device, and thus the interface design for the notebook computer can be remarkably simplified since it needs to support only a few interfaces most commonly used. In fact, the docking station has been becoming one of the most important attachments in the field of the notebook computer.
FIG. 1 is a schematic diagram of a USB docking station. As shown in FIG. 1, one side of the USB docking station is connected to a notebook computer via a USB bus, and the other side thereof is coupled to an external storage device, such as a SD card, and an image capture device, such as a computer camera. The docking station converts data signals from the notebook computer into a data format adapted to the external storage device which stores the data. Also, the acquired image signals is obtained from the image capture device and transferred to the host via USB or UWB. Since other types of interfaces in the docking station, such as parallel port, Ethernet interface and the like, have a low data rate, it is easy to implement conversion from USB/UWB to these interfaces. Unfortunately, there has not been any mature solution for USB/PCIe or UWB to support a second display device, that is, for the conversion from USB/UWB/PCIe to VGA/DVI/Displayport, etc.
According to Patent Reference 1 (US2004117538), the video card in a host is removed, and display signals generated by OS are directly outputted to a USB interface. And, the signals are transmitted from the interface to another remote module, in which VGA signals are regenerated from the transmitted signals and outputted directly to a VGA display device.
Patent Reference 2 (US2002135584) discloses a video graphic adapter which drives a sub display device of a dual-mode display device with USB interface. In Patent Reference 2, video signals outputted from USB are directly stored in a memory area, and the stored video signals are converted into analog VGA signal output by a D/A converter.
Furthermore, video needs to be transferred wirelessly to a remote terminal for display in many situations, for example, the communication between a wireless projector and a notebook computer. In this case, the notebook computer needs to perform a real-time acquisition of screen data and deliver the data wirelessly to the projector for output. Most of schemes for wireless display are based on such wireless technology as defined in IEEE802.11, however. In this way, the high throughput required by the display device cannot be well achieved due to the bandwidth of IEEE802.11, and thus it is necessary to employ a deeply lossy compression scheme. This would result in the problem that the displayed image cannot resemble and synchronize with the original one very well, leading to the degrading of screen quality and color distortion. Meanwhile, the above scheme burdens both of the computer and the display device with a heavy computational load, and thus affects the system performance to a great extent. Moreover, cost tends to be uncontrollable, since the display side usually requires a typical embedded system including CPU/OS/DSP to retrieve the video and output. In conclusion, because of the limited bandwidth of the existing 802.11 system, screen data of high-quality cannot be transmitted timely to the display device side while the computer is playing real-time video, especially video of high-quality.